Lubricating oil thickened to a grease consistency with a mixture of a spiro hydantoin and a siliceous thickening agent



United States Patent LUBRICATING OIL THICKENED TO A GREASE CONSISTENCY WITH A MIXTURE OF A SPIRO HYDANTOIN AND A SILICEOUS THICKENING AGENT Joseph J. McGrath, Monroeville, and John P. Pellegrini,

Jr., Pittsburgh, Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Filed July 29, 1959, Ser. No. 830,199 12 Claims. (Cl. 252-495 This invention relates to improved lubricating compositions and more particularly to lubricants suitable for high temperature lubrication.

The trend in design of modern aircraft has accentuated the need for greases which will lubricate anti-friction bearings operating at high rotational speeds and high temperatures. While considerable progress has been made in recent years in producing improved aircraft greases some difficnlty has been encountered in producing a grease which will effectively lubricate bearings operating at high rotational speeds and high temperatures for prolonged periods of time. Conventional aircraft greases currently available have failed to meet the stringent requirements on such a lubricant. I

We have discovered that a lubricating composition having improved lubricatingcharacteristics for an extended period of time when used to lubricate bearings operating at an elevated temperature under high rotational speeds can be obtained by incorporating into a lubricating oil in oil thickening proportions a mixture of a spiro hydantoin having the following formula:

wherein R is selected from the group consisting of aryl radicals and butadienylene radicals imparting aromatic unsaturation to the compound and a secondary organophilic siliceous oil thickening agent. Thus, the improved lubricating composition of our invention comprises a dispersion in a lubricating oil of a suflicient amount to thicken the lubricating oil to a grease consistency of a mixture of a spiro hydantoin of the type designated by the above structural formula and an organophilic siliceous oil thickening agent.

The amount of the combined spiro hydantoin and the organophilic siliceous material which we. use is an amount suflicient to thicken the lubricating 'oil to a grease consistency. In general, this amount comprises about to about 60 percent by weight of the total composition. The weight ratio of the spiro hydantoin compound to the organophilic siliceous material will vary depending upon the characteristics desired in the ultimate composition. In general, however, the ratio of the spiro hydantoin compound to the organophilic siliceous material is between about 1:1 and about 20:1.

It should be understood that the spiro hydantoin designated by the above structural formula can contain other radicals selected from the group consisting of hydrogen and hydrocarbon radicals. Thus, the spiro hydantoins with additional radicals may be represented by the following formula:

the group consisting of hydrogen, alkyl (e.g., methyl,

ethyl, propyl, butyl and pentyl), aryl (e.g., phenyl and naphthyl), aralkyl (e.g., benzyl) and alkaryl (e.g.,tolyl) radicals.

It will be noted that the substituent designated as R- is such that the spiro hydantoin will always contain at least one aryl radical. So long as this requirement is satisfied, the remaining substituents may be hydrogen, alkyl, aryl, aralkyl, alkaryl or butadienylene radicals. When an alkyl radical is present, it preferably contains from 1 to 5 carbon atoms. When an alkaryl or an aralkyl radical is present, the alkyl portion of the alkaryl and aralkyl radicals preferably contains not more than 2 carbon atoms. More than 5 carbon atoms in the alkyl group and more than 2 carbon atoms in the alkyl portion of the alkaryl and aralkyl radicals are undesirable in that the thermal. stability of the spiro hydantoin is deleteriously affected where the lubricant produced therefrom is subjected to a high temperature and high rotational speeds over extended periods of time.

Spiro hydantoins within the above general classification are as follows:

' l-phenylspiro (cyclopentane-S,5'-hydantoin) 2-phenylspiro (cyclopentane-S-S'-hydantoin) 3-phenylspiro (cyclopentane-S,5-hydantoin) 4-phenylsp'iro (cyclopentane-5,5'-hydantoin) 1,2-diphenylspiro (cyclopentane-5,5'-hydantoin) 2,3-diphenylspiro (cyclopentane-S,5'-hydantoin) 1,2,3-triphenylspiro (cyclopentane-5,5-hydantoin) 1,2,3,4-tetraphenylspiro (cyclopentane-S,5'-hydantoin) l-phenylspiro (cyclopentene-5,5'-hydantoin) 2-phenylspiro (cyclopentene-S,5'-hydantoin) 3-phenylspiro (cyclopentene-S,5'-hydantoin) 4-phenylspiro (cyclopentene-S,s' hydantoin) 1,2-diphenylspiro (cyclopentene-S,5-hydantoin) 2,3-diphenylspiro (cyclopentene-5,5'-l1ydantoin) 1,2,3-triphenylspiro (cyclopentene-5,5'-hydantoin) 1,2,3,4-tetraphenylspiro (cyclopentene-5,5'-hydantoin) l-phenylspiro (cyclopentadiene-S,5-hydantoin) 2-phenylspiro (cyclopentadiene-S,5'-hydantoin) 3-phenylspiro (cyclopentadiene-S,5'-hydantoin) 4-phenylspiro (cyclopentadiene-S,5'-hydantoin) 1,2-diphenylspiro (cyclopentadiene-S,5-hydantoin) 2,3-diphenylspiro (cyclopentadiene-S,5'-hydantoin) 1,2,3-triphenylspiro (cyclopentadiene-5,5'-hydantoin) l,2,3,4-tetraphenylspiro (cyclopentadiene-S,5'-hydantoin) l-phenyl-Z-methylspiro (cyclopentane-5,5'-hydantoin) 1-phenyl-2,3-dimethylspiro (cyclopentane-5,5-hydantoin) 1,4-diphenyl-2,3-dimethylspiro (cyclopentane-5,5'-hydantoin) 1,2,3,4 tetraphenyl 1,2,3,4-tetramethylspiro (cyclopen- (cyclopentane-5,5'-hydan- (cyclopentane-5,5-hydantoin) 3 1,4 diphenyl-2,3-dinaphthylspiro (cyclopentane-S,5'-hydantoin) 1- naphthylspiro (cyclopentane-S,5'-hydantoin) 2,3-dinaphthylspiro (cyclopentane-S,5'-hydantoin) l-phenyl-Z-benzylspiro (cyclopentane-S,5'-hydantoin) 1-pl1enyl-2,3-dibenzylspiro (cyclopentane-S,5-hydantoin) 1,4-diphenyl-2,3-dibenzylspiro (cyclopentane-5,5-hydantoin) 1-phenyl-2-tolylspiro (cyclopentane-5,5'-hydantoin) 1-phenyl-2,3-ditolylspiro (cyclopentane-5,5'-hydantoin) It will be recognized that the last three compounds in the above list are examples wherein R is a butadienylene radical and the remaining substituents designated as R are either hydrogen or butadienylene radicals.

The amount of the spiro hydantoin used may vary over wide limits depending upon the particular oil with which the hydantoin compound is to be blended and upon the properties desired in the final lubricating composition. While as much as 50 percent by weight of the total composition may comprise the hydantoin compound, we prefer to use smaller amounts, that is, in the order of about 10 to 40 percent by weight. It should be understood, however, that, depending upon the consistency of the composition desired and upon the organo philic siliceous material used in combination therewith, less than 10 percent or more than 50 percent of the hydantoin compound may be employed.

The spiro hydantoin compounds can be prepared according to known chemical procedures. Neither the compounds per se nor their preparation constitutes any portion of the invention. For example, the aryl substituted C spiro hydantoin compounds can be prepared by heating the corresponding aryl substituted C ketone (cyclopentane-5,5hydanwith sodium cyanide and ammonium carbonate. The re action mass thus formed is acidified to give the desired spiro hydantoin which thereafter can be subjected to a conventional purification treatment.

It should be understood that the spiro hydantoin compounds can contain other substituents attached to the 0;, ring provided, of course, that said other substituents do not adversely affect the beneficial oil thickening properties of the spiro hydantoin compounds. For example, we have obtained an excellent grease composition 'in which the primary thickener was 2,3-diphenyl-3-hydroxyspiro (cyclopentene-S,5-hydantoin).

, The following illustrative examples will serve to demonstrate the preparation of some of the specific spiro sodium cyanide.

hydantoin compounds which can be used in preparing grease compositions of the present invention.

AMPLE I 2,3-diphenyl-3-hydr0xyspiro' (cyclopentene-S ,5

hydantoin) To 84 grams (0.3 mole) of 3,4-diphenylcyclopentene- 4-ol-2-one in 1250 milliliters of 50% ethanol were added 115.3 grams (1.2 moles) of ammonium carbonate and 29.4 grams (0.6 mole) of sodium cyanide. The mixture thus formed was heated at 60 C. for thirteen hours. The mixture was then acidified under a hood with hydrochloric acid and concentrated to approximately one-third the original volume. After chilling in an ice bath, the crystalline product was filtered from the mixture and recrystallized from ethanol to give 2,3-diphenyl-3- hydroxyspiro (cyclopentene-5,5'-hydantoin) melting at 260-265 C. (500509 F.).

EXAMPLE II Spiro (indan-1,5'-hydant0in) -Seventy-five grams (0.57 mole) of l-indanone was dissolved in 1400 milliliters of 50% ethanol. To the solution thus formed were added 74.2 grams (1.14 moles) of potassium cyanide and 219.1 grams (2.28 moles) of ammonium carbonate. The mixture thus formed was heated at 58-60 C. for eight hours. The

mixture was then acidified under a hood with hydro-- chloric acid and chilled in an ice bath. The crystalline product was filtered from the mixture and the filtrate was concentrated to yield a second crop of crystals. Both crops were recrystallized from 95% ethanol to give spiro (indan-l,5-hydantoin) melting at 240 C. (464 F).

EXAMPLE III Spiro (fluorene-9,5'-hydantoin) To 200 grams (1.1 moles) of 9-fluorenone in 3500 milliliters of 50% ethanol were added 422 grams (4.4 moles) of amonium carbonate and 108 grams (2.2 moles) of The mixture thus formed was heated at 60 C. for twelve hours. The mixture was then acidified under a hood with hydrochloric acid and concentrated to approximately one-third the original volume. After chilling in an ice bath, the crystalline product was filtered from the mixture. The crystals were dissolved in 10% sodium hydroxide (2 mL/g. of product), treated with decolorizing carbon, filtered and the filtrate acidified with hydrochloric acid. The crystalline product was then filtered and washed free of acid. The melting point of the purified spiro (fluorene-9,5-hydantoin) thus obtained was 324331 C. (615628 F.). The product decomposes on heating to its melting point.

The organophilic siliceous materials which we employ in the lubricating composition of this invention are exemplified by bentonite-organic base compounds known commercially as Bentones and finely-divided organo-siliceous solids such as the esterified siliceous solids known commercially as Estersils. The amount of the organophilic siliceous material employed may vary over wide limits depending upon the particular compound employed, the particular oil with which the siliceous compound is blended and the properties desired in the ultimate composition. While the organophilic siliceous material may comprise as much as 20 percent by weight of the total composition, we prefer to use smaller amounts, that is, in the order of about 1 to about 10 percent by weight. It should be understood, however, that depending upon the consistency of the composition desired and upon the spiro hydantoin content of thecornposition less than 1 percent or more thzin 10 percent of the organophilic siliceous material can be employed.- 4

Typical bentonite-organic base compounds employed in accordance with the invention are compounds composed of a. montmorillonite mineral in which at least a part of the cation content of the mineral has been reatoms either naturally or after treatment, constitute the raw materials employed in making the bentonite-organic base compounds used in the compositions of this invention. So far as known, all naturally occurring montmorillonites contain some magnesium and certain of them, as exemplified by Hector clay, contain such a high percentage of magnesium that they largely have magnesium in place of the aluminum content characteristic of the more typical montmorillonites. i

The bentonite-organic base compounds are preferably prepared as described in U.S. Patent No. 2,033,856, issued March 10, 1936, by bringing together the bentonite and theorganic base in the presence of aqueous mineral acid to effect base exchange. The organic bases should preferably be titratable with mineral acids. Among these reactive bases are many alkaloids, and cyclic, aliphatic, and heterocyclic amines. The bentonite-organic base compounds used in preparing the lubricating compositions of this invention are preferably those prepared by bringing together a bentonite clay and such organic bases as aliphatic amines, their salts, and quaternary ammonium salts. Examples of such amines and salts are: decy1a-' mine, dodecylamine, tetradecylamine, hexadecylamine,

octadecylamine, hexadecyl ammonium acetate, oct-adecyl ammonium acetate, dimethyldioctyl ammonium acetate, dimethyldidodecyl ammonium acetate, dimethyldodecylhexadecyl ammonium acetate, dimethyldicetyl ammonium acetate, dimethylhexadecyloctadecyl ammonium acetate, dimethyldioctadecyl ammonium acetate, and the corresponding chlorides and quaternary ammonium chlorides. The organic bases employed should be such as to impart substantial organophilic properties to the resulting compounds. The preferred bentonite compounds are prepared from quaternary ammonium compounds in which the N-substituents are aliphatic groups containing at least one alkyl group with a total of at least 10 to 12 carbon atoms. When aliphatic amines are used they preferably contain at least one alkyl group containing at least 10 to 12 carbon atoms.

While the long chain aliphatic amine bentonite compounds are readily dispersible in practically all oil bases, dispersion of the short' or single chain aliphatic amine bentonite compounds, in the oil, particularly mineral oils and synthetic oils other than ester lubricants, can be'facilitated by the use of one or more solvating agents. Suitable solvating agents are polar organic compounds such as organic acids, esters, alcohols, ethers, ketones, and aldehydes, especially low molecular weight compounds of these classes. Examples of suitable solvating agents are: ethyl acetate, acetic acid, acetone, methyl alcohol, ethyl alcohol, benzoyl chloride, butyl stearate, cocoanutdoil,

cyclohexanone, ethylene dichloride, ethyl ether, furfural, isoamyl acetate, methyl ethyl ketone, and .nitrobenzene. In cases where the use of a solvating agent is desirable for effecting more rapidand more complete dispersion of the organic bentonite compound in the oil, ordinarily only a relatively small amount of such agent may be necessary. However, as much as about 50 percent byweight based on the amount of the bentonite compound can be used.

Typical estersils employed in accordance with the invention are described in US. Patent No. 2,657,149, issued October 27, 1953, to R. K. Iler. The estersils are organophilic solids madeby chemically reactingvprimary or secondary alcohols with certain siliceous solids. In brief, the estersils are powders or jpulverulent materials the 6' age specific surface area of from 1 to 900 square meters per gram. The substrate has a surface of silica which is coated with OR' groups, the coating of -OR' groups 7 being chemically bound to the silica. R is a hydrocarbon radical of a primary or secondary alcohol containing from 2 to 18 carbon atoms. The carbon atom attached to the oxygen is also attached to hydrogen.

The estersil substrates are solid inorganic siliceous materials which contain substantially no chemically bound organic groups prior to esterification. The substrates are in a supercolloidal state of subdivision, indicating that whatever discrete particles are present are larger than colloidal size. In general, the supercolloidal substrates have at least one dimension of at least 150 millimicrons.

The supercolloidal particles may be aggregates of ulti mate units which are colloidal in size.

The estersils which we employ are advantageously those in which the ultimate units have an average diameter of 8 to 10 millimicrons. The substrates advantageously have specific surface areas of at least 25 square meters per gram and preferably at least 200 square meters per gram.

The estersils made from most alcohols become organophilic when they contain more than about 80 ester groups per 100 square millimicrons of surface of internal structure. They become more organophilic as the ester groups increase. Thus, the products which contain 100 ester groups per 100 square millimicrons of substrate surface are more organophilic than those that contain only 80 ester groups. When the estersils contain at least 200 ester groups per 100 square millimicrons of substrate surface, the estersils not only are organophilic but also are hydrophobic. Thus, the more highly esterified products are particularly desirable where the lubricant made therefrom comes in contact with water. When C to C alcohols are used in preparing the estersils, the estersils may contain from 300 to 400 ester groups per 100 square millimicrons of substrate surface. Thus, a

' preferred group of estersils are those prepared from the C to C alcohols.

The estersils, as noted above, are powders or pulverulent materials. The estersil powders are exceedingly fine, light and fiutfy. The bulk density of preferred estersils is in the order of 0.15 to 0.20 gram per cubic centimeter at 3 pounds per square inch and in the order of about 0.30 gram per cubic centimeter at 78 pounds per square inch. The estersils are availablecommercially and thus the estersils per se and their preparation constitute no part of this invention.

The lubricating oil in which the spiro hydantoin and the secondary thickening agent are incorporated is preferably a lubricant of the type best suited for the particular use for which the ultimate composition is designed.

Since many of the properties possessed by the lubricating oil are imparted to the ultimate lubricating composition, we advantageously employ an oil which is thermally stable at the contemplated lubricating temperature. Some mineral oils, especially hydrotreated mineral oils, are sufiicientlystable to provide a lubricating base for preparingjlubricants to be used under moderately elevated temperatures. Where temperatures in the order of 400 F. and above are to be encountered, synthetic oils form a preferred class of lubricating bases because of their high thermal stability.' By the term synthetic oil we mean an oil of non-mineral origin. The synthetic oil can be an organic ester which has a majority of the properties of a hydrocarbon oil of lubricating grade such as di2-ethylhexyl.'sebacate, dioctyl phthalate and dioctyl azelate. Instead of an organicester, we can use polymerized olefins, copolymers of alkylene glycols and alkylene oxides, polyorgano siloxanes and the like.

The liquid polyorgano siloxanes because of their exinternalstructure or.substrate of which have an averphilic siliceous materials are, added. These polyorgano siloxanes are known commercially as silicones and are made up of silicon and oxygen atoms wherein the silicon atoms may be substituted with alkyl, aryl, alkaryl, aralkyl and cycloalkyl radicals. Exemplary of such compounds are the dimethyl silicone polymers, diethyl silicone polymers, ethyl-phenyl silicone polymers and methyl-phenyl silicone polymers.

if desired, a blend of oils of suitable viscosity may be employed as the lubricating oil base instead of a single oil by means of which any desired viscosity may be secured. Therefore, depending upon the particular use for which the ultimate composition is designed, the lubricating oil base may be a mineral oil, a synthetic oil, or a mixture of mineral and/ or synthetic oils. The lubricating oil content of the compositions prepared according to thisinvention comprises about 40 to about 90 percent by weight of the total composition.

In compounding the compositions of the present invention, various mixing and blending procedures may be used. In a preferred embodiment of the invention, the lubricating oil, the spiro hydantoin and the secondary thickener together with a solvating agent and conventional lubricant additives, if desired, are mixed together at room temperature for a period of 10 to 30 minutes to form a slurry. During this initial mixing period some thickening is evidenced. Some lumps may be formed. The slurry thus formed is then subjected to a conventional milling operation in a ball mill, a colloid mill, homogenizer or similar device used in compounding greases to give the desired degree of dispersion. In the illustrative compositions of this invention, the slurry was passed twice, by means of a pump, through a Premier Colloid Mill set at a stator-rotor clearance of 0.002 inch. Maximum thickening occurred on the second pass through the mill.

The lubricating composition of this invention can contain conventional lubricant additives, if desired, to improve other specific properties of the lubricant without departing from the scope of the invention. Thus, the lubricating composition can contain a filler, a corrosion and rust inhibitor, an extreme pressure agent, an antioxidant, a metal deactivator, a dye, and the like. Whether or not such additives are employed and the amounts thereof depend to a large extent upon the severity of the conditions to which the composition is subjected and upon the stability of the lubricating oil base in the first instance. Since the poly-organo siloxanes, for example, are in general more stable than mineral oils, they require the addition of very little, if any, oxidation inhibitor. When such conventional additives are used they are generally added in amounts between about 0.01 and percent by Weight based on the weight of the total composition.

In order to illustrate the lubricating characteristics at an elevated temperature and high rotational speeds, grease compositions of the invention were-subjected to the test procedure outlined by the Coordinating Research Council Tentative Draft (July 1954), Research Technique for the Determination of Performance Characteristics of Lubricating Grease in Antifriction Bearings at Elevated Temperatures, CRC Designation L-35. According to this procedure, 3 grams of the grease to be tested are placed in a bearing assembly containing an eight-ball SAE No. 204 ball bearing. The bearing assembly which is mounted on a horizontal spindle is subjected to a radial load of 5 pounds. The portion of the spindle upon which the test bearing assembly is located is encased in a thermostatically controlled oven. By this means the temperature of the bearing can be maintained at a desired elevated temperature which in the tests reported hereinafter was 400 F.- The spindle is driven by a constant belt-tension motor drive assembly, capable of giving spindle speeds up to 10,000 revolutions per minute. The spindle is operated on a cycling schedule consisting of aseries of. periods,..each period consisting of 20 hours running time and 4 hours shutdown time. The test concondition at the test temperature; (2) an increase in temperature at the test bearing of 20 F. over the test temperature during any portion of a cycle; or (3) the test bearing locks or the drive belt slips at the start or during the test cycle.

The oil used in preparing the lubricating compositions summarized in Table I was a synthetic oil known commercially as DC 550 Fluid marketed by Dow-Corning Corporation. This fluid is a methylphenylsiloxane polymer having as typical characteristics a viscosity at 100 F. of 300 to 400 SUS, a viscosity-temperature coefiicient of 0.75, a freezing point of -54 F., a flash point of 600 F. and a specific gravity 25 C./25 C. of 1.08.

In preparing the lubricating compositions, the oil, the spiro hydantoin and the dimethyldicetylammonium bentonite were mixed at room temperature for a period of 10 to 30 minutes. The slurry thus formed was passed twice through a Premier Colloid Mill set at a stator-rotor clearance of 0.002 inch. The thickened lubricating compositions thus prepared had the following approximate make-up and properties.

TABLE I Composition, Percent By Weight A B Lubricating Oil:

DC 550 Fluid 63 63 2,3-Diphenyl-3-hydroxyspiro n The test was stopped at the end of 981 hours although no bearing failure was encountered.

The long performance life of the compositions of the invention at a high rotational speed and a high temperature is self evident from the above data.

An additional composition was prepared consisting of 66.4 percent DC 550 Fluid, 30 percent spiro (indan-1,5- hydantoin) and 3.6 percent dimethyldicetylammonium bentonite. When the additional composition was subjected even to a more severe test using Pope spindles and an MRC 204 8-17 hearing at 400 F. and 20,000 revolutions per minute a performance life of 690 hours was obtained.

Other lubricating compositions within the scope of the invention are illustrated in- Table II. G.E. Silicone 81717 is marketed by General Electric Company and is a water-white to amber liquid polymer of the general formula It has a viscosity at -65 F. of 3487 centistokes, at 0 F. of 390 centistokes, at F. of 71.3 centistokes, at 210 F. of 22 centistokes and at 700 F. of 1.9 centistokes.

Estersil GT is marketed by E. I. du Pont de Nemours and Company and consists of an amorphous silica coated with approximately 340 butoxy groups per 100 square millimicrons of surface. The product is a white granular solid comprising 88 to 89 percent Si0 having an ultimate particle size of 8 to 10 millimicrons. The surface area comprises about 285 to 335 square meters per gram. The product has a pH in a 50-50 methanol-water mix- 9 ture of 8.0 to 9.0 and a bulk density of 1 9 to 20 pounds per cubic foot. I

unsaturation to the compound and an organophilic bentonite-organic base compound, the weight ratio of the TABLE 11 Composition, Percent By Weight Lubricating Oil: 7

DC 550 Fluid G.E. Silicone 81717 Di-Z-ethylhexyl sebacate Spiro Hydantoin:

l-Phenylspiro (cyclopentane-5.5-hydantoin) 1- Phenyl 2-methylspiro (cyclopentene 5,5

hydantoin) 2,3- iphenylspiro (cyclopentadlene-5,5-hydantoin Spiro (indene-l,5-hydantoin) Secondary Thickener:

Dimethyldicetylammoulum bentonite. Dimethyldidodecylammonlum bentonite. Dlmethyldioctylammonium bentrmite Dlmethyldioctadocylammonium bentonite.": Estersil GT Ratio of spiro hydantoin to secondary thickener wherein R is selected from the group consisting of aryl radicals and butadienylene radicals imparting aromatic unsaturation to the compound and an organophilic siliceous oil thickening agent, the weight ratio of the spiro hydantoin to the organophilic siliceous material in said mixture being about 1 1 to 1.

2. The lubricating composition of claim 1 wherein the combined spiro hydantoin and organophilic siliceous material comprises about 10, to 60 percent by weight of the total composition.

3. The lubricating composition of claim 1 wherein the lubricating oil is a polyorgano siloxane.

4. The lubricating composition of claim 1 wherein the organophilic siliceous oil thickening agent is a bentoniteorganic base compound.

5. The lubricating composition of claim 1 wherein the organophilic siliceous oil thickening agent is an organophilic estersil comprising a supercolloidal substrate coated with OR groups, the substrate having a surface of silica and having a specific surface area of from 1 to 900 square meters per gram, the coating of -OR' groups being chemically bound to said silica and R being a hydrocarbon radical of from 2 to 18 carbon atoms, wherein the carbon attached to oxygen is also attached to hydrogen.

6. A lubricating composition comprising a dispersion in a liquid polyorgano siloxane of a sufiicient amount to thicken the polyorgano siloxane to a grease consistency of a mixture of a spiro hydantoin having the following formula:

NHCO

wherein R is selected from the group consisting of aryl radicals and butadienylene radicals imparting aromatic spiro hydantoin to the organophilic bentonite.-organic base compound in said mixture being about 1 :'1 to 20: 1.

7. A lubricating composition comprising a dispersion in a lubricating oil of a sufi'icient amount to thicken the lubricating oil to a grease consistency of a mixture of a spiro hydantoin having the following formula:

wherein R is selected from the group consisting of aryl radicals and butadienylene radicals imparting aromatic unsaturation to the compound and R is selected from the group consisting of hydrogen, alkyl, aryl, aralkyl and alkaryl radicals and an organophilic bentonite-organic base compound, the weight ratio of the spiro hydantoin to the organophilic bentonite-organic base compound in said mixture being about 1 1 to 20 1.

8. The lubricating composition of claim 7 wherein the spiro hydantoin is spiro (indan-1,5'-hydantoin) and the bentonite.-organic base compound is dimethyldicetylammonium bentonite.

9. The lubricating composition of claim 7 wherein the spiro hydantoin is spiro (fluorene-9,5'-hydantoin) and the bentonite-organic base compound is dimethyldicetylammonium bentonite.

10. The lubricating composition of claim 7 wherein the spiro hydantoin is 2,3-diphenyl-3-hydroxyspiro (cyclopentene-5,5'-hydantoin) and the bentonite-organic base compound is dimethyldicetylammonium bentonite.

11. A lubricating composition comprising a dispersion in a liquid polyorgano siloxane of a sufficient amount to thicken the polyorgano siloxane to a grease consistency of a mixture of a spiro hydantoin having the following formula: I

wherein R is selected from the group consisting of aryl radicals and butadienylene radicals imparting aromatic unsaturation to the compound and an organophilic estersil, the weight ratio of the spiro hydantoin to the organophilic estersil in said mixture being about 1 1 to 20 1, said organophilic estersil comprising a supercolloidal substrate coated with --0R groups, the substrate having a surface of silica and having a specific surface area of from 25 to 900 square meters per gram, the coating of 11 --OR groups being chemically bound to said silica and R being a hydrocarbon'radical 'of'from 3 to 6 'carbon atoms, wherein the carbon atom attached to oxygen is also attached to hydrogen.

12. The lubricating composition of claim 11 wherein the spiro hydantoin is spiro (indan-l,5-hydantoin) and the organophilic estersil is an amorphous silica coated with about 340 butoxy groups per 100 square millimicrons of surface.

UNITED STATES PATENTS 820,763 Hughes et a1. Jan. 21, 1958 5 2,875,152 Van Scoy Feb. 24, 1959 2,917,457 Preiss Dec. 15, 1959 OTHER REFERENCES Chem. Abstracts, vol. 41, page 7392b, 1947. Chem. Abstracts, vol. 47, page 589441, 1953. 

1. A LUBRICATING COMPOSITION COMPRISING A DISPERSION IN A LUBRICATING OIL OF A SUFFICIENT AMOUNT TO THICKEN THE LUBRICATING OIL TO A GREASE CONSISTENCY OF A MIXTURE OF A SPIRO HYDANTOIN HAVING THE FOLLOWING FORMULA: 